The present invention relates to a process for producing a nitrogen-alloyed stainless steel layer on steel by laser surface alloying, and in particular to a process for producing a nitrogen-alloyed stainless steel layer on steel by applying mixed metal powders containing nitride to the steel, and thereafter treating the steel with laser beams.
Due to their superior mechanical strength and corrosion resistance, in particular pitting corrosion resistance, nitrogen-containing stainless steels have drawn the attention of many researchers. Conventionally, nitrogen containing stainless steels are manufactured by, for example, pressurized induction melting, plasma remelting, hot isostatic pressure melting and pressurized electroslag refining methods. However, these methods all involve high temperature and high pressure processes, and therefore the process control is difficult.
Ionic nitriding and plasma nitriding methods are commercially utilized methods for forming nitride layers on the surface of steels to improve the abrasion and corrosion resistance thereof. However, these methods must be applied in a vacuum ambient, and consume an undesirable amount of time and energy.
Steels usually have low corrosion resistance. If a nitrogen containing stainless steel layer can be formed on steels, topical corrosion, such as pitting corrosion and crevice corrosion resistance can be improved. Using the Laser Surface Alloying(LSA) method to form a nitrogen containing stainless steel layer on the surface of steels, from the view of saving energy and reducing production costs, should be the best method for improving the corrosion resistance of steels. Because by this method, not only can the moderate strength and toughness of the steel material be retained, but the corrosion resistance can also be improved.